Line up allowance
Thread Starter
Line up allowance
Hi there,
Our Performance Manual tells us that the line up allowance for our 737-800 aircraft is 27m (ASDA) and 11m (TORA) . For an intersection departure, where does that 11m start from? Is it abeam the centreline of the taxiway ( where it enters the runway) even if the taxiway you are entering on is a high speed exit?
If someone could point me towards an ICAO doc that explains I would be grateful.
Cheers
Our Performance Manual tells us that the line up allowance for our 737-800 aircraft is 27m (ASDA) and 11m (TORA) . For an intersection departure, where does that 11m start from? Is it abeam the centreline of the taxiway ( where it enters the runway) even if the taxiway you are entering on is a high speed exit?
If someone could point me towards an ICAO doc that explains I would be grateful.
Cheers
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Sir George has it; this was clarified recently in the UK's freely-published CAP.
Practically-speaking, following the taxiway centreline and then a sharp ninety-degree turn onto the runway centreline will give you the appropriate distance ahead. The crucial thing is not to follow the lead-off line as though it's a lead-on line. An exception would be doing so at a trot or canter, with the intention of a rolling takeoff, when a gentler turn at higher speed leaves you going faster at a particular point than you would have been had you turned on sharply at low speed. Doing so whilst spooling up may be VERY bad for some engines.
It's a complete mystery to me why ICAO doesn't make its safety standards available to people to read and learn from.
Practically-speaking, following the taxiway centreline and then a sharp ninety-degree turn onto the runway centreline will give you the appropriate distance ahead. The crucial thing is not to follow the lead-off line as though it's a lead-on line. An exception would be doing so at a trot or canter, with the intention of a rolling takeoff, when a gentler turn at higher speed leaves you going faster at a particular point than you would have been had you turned on sharply at low speed. Doing so whilst spooling up may be VERY bad for some engines.
It's a complete mystery to me why ICAO doesn't make its safety standards available to people to read and learn from.
Last edited by TheiC; 14th Dec 2014 at 07:44.
Thread Starter
Thanks a lot . I found the nice drawing in the cap which was a bit different to what I expected in that it used the downwind side of the taxiway as the reference for extending through to the runway centreline.
I am in NZ but imagine we have adopted ICAO for most things aviation.
Thanks again.
I am in NZ but imagine we have adopted ICAO for most things aviation.
Thanks again.
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Unless you are performance limited, why not plan for an intersection departure and use the next longest one (or more) or reduce your TORA/TODA by 100m or so? Then you don't have to scrub your tyres and strain the gear graunching the aircraft around on the runway to squeeze every metre available. It also allows for a smooth, gentle line up and rolling takeoff.
Thread Starter
Unless you are performance limited, why not plan for an intersection departure and use the next longest one
or reduce your TORA/TODA by 100m or so?
Thanks for the input.
Unless you are performance limited, why not plan for an intersection departure and use the next longest one (or more) or reduce your TORA/TODA by 100m or so? Then you don't have to scrub your tyres and strain the gear graunching the aircraft around on the runway to squeeze every metre available. It also allows for a smooth, gentle line up and rolling takeoff.
